|
|
Owner: Geez, I typed a book and then something I did erased it. So, here goes again.
I actually have a 1994 Cobra. There are three distinct driveline noise conditions;
First, after sitting all night there is a loud bang when backing up. Like something is stuck and releasing as the car begins to move. We have been all through the braking system.
Second, after downshifting and coming to a complete stop, when I put the car in first gear and begin to release the clutch, just as the clutch makes contact but before there is any real torque on the driveline, there is a loud bang in the driveline. It sounds like there is a bunch of slop being taken up in the gears somewhere. I also feel like there is a great deal of gear slop at high speed if I just take my foot off the gass and reapply it. I have changed the U-Joints and checked the gear lash in the differential. It all appears to be in limits. Another mechanic said it could be Pinion shaft bearings though.
Third, there is a whine at road speed at neutral torque. Adding gas or taking my foot all the way off stops the noise. It is right at that balance point of no torque.
I would like to make sure it is the rear end or the Transmission before I go about rebuilding either one. Both are costly especially if I choose the wrong one to fix.
Thanks
Technican: Is this a factory stock aluminum drive line.If so this may be one of the two piece drivelines I used to run into while working at a dealership.The internal portion somtimes comes apart causing noise and vibration.As far as the road whine, the differential along with its bearings need to be checked for proper gear lash and torlerance.Lastly, your tranny itself could be at question.You say that under no torque is when it is most noticeable.The driveline makes for a great resonator for sound coming from both the tranny and differential.If you have already checked gear lash and the tranny is working good, I'd kind of eye the driveline first.
Paul
Owner: Paul,
No it is not the Alumium Driveline. Apparently in 1994 there were very minor differences between the Mustang GT and the Cobra (although some are very odd like the lower radiator hose).
I have the factory Shop manual for this car and used the differential Lash check procedure from there. Remove drive shaft and lock pinion shaft. Raise one wheel of rear end. Using torque wrench apply pressure one way then the other and measure the movement of the free wheel. It was within limits. I am thinking that this would not account for lateral movement in a pinion shaft bearing though.
Other folks have said something about Tranny bearings. Tranny bearings would not account for the lash I feel at high speed when I reverse thrust on the drive line by backing off the throttle and reapplying it.
It still feels like "Could be tranny, could be differential" starting to feel like "could be both".
I bought this car with 120, 000 miles on it and it was poorly maintained by the original/previous owner. I have spent a fortune so far and as I said it now runs great. Compression is even and over 150lbs in all 8 cylinders so I am willing to keep going. Like I said, once I tear either unit open, at this mileage level, there will be no alternative but to continue with a rebuild anyway.
Perhaps we should approach this differently. Assuming I have to rebuild both units, what parts should I order ahead of time (all of the parts ordinarily changed in a rebuild) for each unit?
At least this way, I can reduce my down time and make an attempt at a budget.
Thanks
Technican: O.K., you took one piece of the puzzle off the plate with the driveshaft issue.And yes its starting to sound like an either or issue between the tranny and differential.120K is not an exceptional amount of miles unless they were abusive ones.The manner in which you discribed in checking lash on differential is a far cry from what a specialist does to determine if the lash is at cause.With the pinion removed, a marking paint is applied to the pinion and then rotated against the the pinion gear to give a true mark of gear to gear mesh.By reading the marks, one can tell if the gears are "feathering"(whineing noise) or "mashing"(growling noise).If neither is the case, and you say you have already replaced U-joints, it would now be the time to start exploring the tranny.As far as parts to order ahead of time, when you're shooting at this many ducks, its; safer to make sure the ones you shoot at are in season.(Theres going to be down time regaurdless, but we're talking of some possibily expensive non-returnable items here.
Paul Here's How To Get Guaranteed Solutions In Minutes
|
